Image sensor with scaler and image scaling method thereof

ABSTRACT

An image sensor is wieldy used in many fields, including medical field and security device. Specifically, the image sensor is most widely used in digital camera and mobile phone. The digital camera and the mobile phone requires capture image of higher resolution and higher quality. However, a preview size of the mobile phone or digital camera requires a small size because of a display limitation. Therefore, a function of reducing an image size or magnifying a specific portion of the picture is essential in the image sensor. Accordingly, there is provided an image sensor with a scaler. The image sensor with the scaler can arbitrarily adjust a size of an image without any additional scaling chip.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/319,553, filed on Dec. 29, 2005, entitled “IMAGE SENSOR WITH SCALERAND IMAGE SCALING METHOD THEREOF”, the entirety of which is incorporatedherein by reference.

FIELD OF THE INVENTION

The present invention relates to a CMOS image sensor; and, moreparticularly, to a CMOS image sensor with a scaler and an image scalingmethod thereof.

DESCRIPTION OF THE RELATED ART

An image sensor is an apparatus to capture images using light sensingsemiconductor materials. Since brightness and wavelength of light froman object are different in their amount according to the reflectionarea, electrical signals from pixels are different from one another.These electrical signals are converted into digital signals, which canbe processed in a digital circuit.

FIG. 1 is a block diagram of an image sensor.

Referring to FIG. 1, the image sensor includes a pixel array 10 with M×Nunit pixels (M and N are positive integers), a timing controller 11, ananalog signal processor 12, an image signal processor 14, and a linememory 13.

The analog signal processor 12 is provided with a correlated doublesampling (CDS) and analog amplifier 121, and an analog-to-digitalconverter (ADC) 122.

The timing controller 11 is called a control and external systeminterface. The timing controller 11 controls an overall operation of theimage sensor using a finite state machine (FSM) and serves as aninterface for an external system. Also, since the timing controller 11has a batch register, it can program contents related to severalinternal operations and controls an overall chip operation according tothe program information.

The pixel array 10 includes M×N unit pixels configured to maximizelight-sensitive characteristics. The pixel array 10 is a core of theimage sensor and detects information about an image inputted from theoutside.

In the CDS and analog amplifier 121, the CDS removes a fixed patternnoise of a pixel using a CDS method, and the analog amplifier converts apixel signal into an electric signal.

The ADC 122 converts an analog voltage detected by each pixel of thepixel array 10 into a digital voltage that can be processed at a digitalsystem.

The line memory 13 stores the digital voltage of the pixel, which isconverted by the ADC 122. The line memory 13 includes a plurality oflines for executing various functions of the image signal processor 14.

The image signal processor 14 executes several functions for improvingthe performance of the image sensor, based on the pixel output valuestored in the line memory 13. Examples of the functions are a colorinterpolation, a color correction, a gamma correction, an auto whitebalance, an auto exposure, and so on.

Generally, a camera system using an image sensor includes an imagesensor and a back-end chip. The image sensor converts an optical signalinto an electric signal, and transfers the corresponding imageinformation. The back-end chip receives the image information from theimage sensor, enhance an image picture, compresses the information, andadjusts an image size. In the image sensor, the number of pixels hasincreased up to million pixels and continuously increases rapidly.However, a preview size of a mobile phone or digital camera requires asmall size because of a display limitation. Therefore, the image scalingbecomes important in the back-end chip.

However, after the image information of one picture from the imagesensor is all stored, the back-end chip has to adjust the image size.Therefore, a long time is taken for the image scaling. An operationspeed of the image sensor is limited due to the speed of the imagescaling processed by the back-end chip. Consequently, a frame rate ofthe image sensor is degraded and a picture is broken in the preview ofthe mobile phone or digital camera.

SUMMARY OF THE INVENTION

It is, therefore, an object of the present invention to provide an imagesensor with an embedded scaling function and an image scaling methodthereof, in which the scaling can be executed without any additionalscaler chip.

In accordance with an aspect of the present invention, there is providedan image sensor including: a pixel array having a plurality of pixelsformed to maximize light sensing characteristic, the pixel array beingconfigured to detect information on an external image; a timingcontroller for controlling an overall operation of the image sensor; ananalog signal processor for converting an analog signal from the pixelarray into a corresponding digital signal under control of the timingcontroller; a line memory for storing the digital signal in line unit;an image signal processor for processing a plurality of images by usingthe digital signal stored in the line memory so as to improveperformance of the image sensor; and a scaler for receiving a scalingfactor of a desired image size from the timing controller andcalculating a scaling ratio so as to adjust an image size, andgenerating a corresponding row/column address and data and scaling theimage stored in the line memory, whereby the image with the desired sizeis outputted.

In accordance with another aspect of the present invention, there isprovided an image scaling method of an image sensor, including:calculating a scaling ratio corresponding to scaling factors (SCALEM,SCALEN) for outputting an image with a desired size, wherein the scalingratio is SCALEM/SCALEN; determining whether to execute a pre-scalingaccording to the scaling ratio; when the pre-scaling is necessary toexecute, executing the pre-scaling to adjust the size of the image;determining whether to execute a post-scaling; when the post-scaling isnecessary to execute, executing the post-scaling to adjust the size ofthe image; and synchronizing image data scaled through the pre-scalingand the post-scaling with an output clock of the image sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention willbecome apparent from the following description of the preferredembodiments given in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a block diagram of an image sensor;

FIG. 2 is a block diagram of a CMOS image sensor in accordance with anembodiment of the present invention;

FIG. 3 is a block diagram of a scaler of FIG. 2;

FIG. 4 is a flowchart diagram illustrating an image scaling algorithm ofthe scaler in FIG. 2;

FIG. 5 is a block diagram of a scaling ratio generator of in FIG. 3;

FIG. 6 is a block diagram of a pre-scaler of FIG. 3;

FIG. 7 is a block diagram of a post-scaler of FIG. 3;

FIG. 8A illustrates an output of the pre-scaler in a full color datalevel when the pre-scaling ratio is 1/4;

FIG. 8B illustrates an output of the pre-scaler in a bayer data levelwhen the pre-scaling ratio is 1/4;

FIG. 9A illustrates an output of the post-scaler in a full color datalevel when the post-scaling ratio is 5/7 with respect to a post 14×14pixel array;

FIG. 9B illustrates an output of the post-scaler in a bayer data levelwhen the post-scaling ratio is 5/7 with respect to a post 14×14 pixelarray; and

FIG. 10 is a flowchart diagram illustrating an algorithm of generatingrow/column addresses for the image scaling.

DETAILED DESCRIPTION OF THE INVENTION

An image sensor with a scaler and an image scaling method thereof inaccordance with exemplary embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of a CMOS image sensor in accordance with anembodiment of the present invention.

Referring to FIG. 2, the CMOS image sensor includes a pixel array 20with M×N unit pixels (M and N are positive integers), a timingcontroller 21, an analog signal processor 22, an image signal processor24, a line memory 23, and a scaler 25.

The analog signal processor 22 is provided with a CDS and analogamplifier 221, and a CDS 222.

The timing controller 21 is called a control and external systeminterface. The timing controller 11 controls an overall operation of theimage sensor using an FSM and serves as an interface for an externalsystem. Also, since the timing controller 21 has a batch register, itcan program contents related to several internal operations and controlsan overall chip operation according to the program information.

The pixel array 20 includes M×N unit pixels configured to maximizelight-sensitive characteristics. The pixel array 20 is a core of theimage sensor and detects information about an image inputted from theoutside.

In the CDS and analog amplifier 221, the CDS removes a fixed patternnoise of a pixel using a CDS method, and the analog amplifier converts apixel signal into an electric signal.

The ADC 222 converts an analog voltage detected by each pixel of thepixel array 20 into a digital voltage that can be processed at a digitalsystem.

The line memory 23 stores the digital voltage of the pixel, which isconverted by the ADC 222. The line memory 23 includes a plurality oflines for executing various functions of the image signal processor 24.

The image signal processor 24 executes several functions for improvingthe performance of the image sensor, based on the pixel output valuestored in the line memory 23. Examples of the functions are a colorinterpolation, a color correction, a gamma correction, an auto whitebalance, an auto exposure, and so on.

The scaler 25 receives a scaling factor for adjusting the image size andcalculates a scaling ratio. Then, the scaler 25 creates row/columnaddress and data corresponding to the scaling ratio and outputs an imagewith a desired size.

FIG. 3 is a block diagram of the scaler 25 illustrated in FIG. 2.

Referring to FIG. 3, the scaler 25 includes a scaling ratio generator250 for determining the scaling ratio according to the scaling factorsSCALEM and SCALEN, a pre-scaler 251 for selectively executing thepre-scaling under control of the scaling ratio generator 250 and thetiming controller 21, a post-scaler 252 for selectively executing thepost-scaling with respect to the pre-scaled image and the non-pre-scaledimage, and an output data synchronizer 253 for synchronizing the scaledimage from the post-scaler 252 with the output clock of the imagesensor.

An operation of the scaler 25 will be described in detail below.

The scaling ratio generator 250 calculates the scaling ratio using thescaling factors SCALEM and SCALEN. The scaling ratio is expressed as

Scaling ratio=SCALEM/SCALEN  (1)

Also, the scaling ratio generator 250 determines a pre-scaler validsignal and a pre-scaling ratio according to the scaling ratio. Thepre-scaler valid signal determines on/off operation of the pre-scaler251.

Only when the pre-scaler valid signal is generated, the pre-scaler 251generates pre-scaler row/column addresses according to the pre-scalingratio calculated by the scaling ratio generator 250. Also, thepre-scaler 251 generates an image of an appropriate size by samplingonly data located at positions matched with the generated addresses.

The post-scaler 252 adjusts a final image size of the image scaler 25.When not passing through the pre-scaler 251, the scaling ratio generatedfrom the scaling ratio generator 250 becomes the post-scaling ratio andthus the size of the final image is adjusted according to the scalingratio. On the contrary, when passing through the pre-scaler 251, thepost-scaling ratio of the post-scaler 252 is given by

Post scaling ratio=[(SCALEM/SCALEN)/Scaling ratio]  (2)

When the pre-scaler 251 is off, the post-scaler 252 receives therow/column addresses from the timing controller 21 to generate newrow/column addresses according to the post-scaling ratio. On thecontrary, when the pre-scaler 251 is on, the post-scaler 252 receivesthe row/column addresses from the pre-scaler 251 to generate newrow/column addresses according to the post-scaling ratio.

Since the output timing of the image sensor due to the post-scaler 252is not constant, the output data synchronizer 253 receives image data ofthe post scaler 252 and then synchronizes the scaled image data with theoutput clock of the image sensor.

FIG. 4 is a flowchart diagram illustrating an image scaling algorithm ofthe scaler of FIG. 2.

Referring to FIG. 4, in the step S901, if scaling factors SCALEM andSCALEN for outputting an image with a desired size are transferredthrough the timing controller 21, a scaling ratio is generated. Then, instep S902, it is determined whether to execute a pre-scaler according tothe scaling ratio.

In step S903, if it is determined that the pre-scaler is necessary toexecute, a pre-scaling using the pre-scaler is performed to adjust theimage size. Then, in step S904, it is determined whether the post-scaleris necessary to execute. In step S905, if the post-scaler is necessaryto execute, a post-scaling is performed through the post-scaler toadjust the image size. If the post-scaler is unnecessary to execute, theimage size obtained through the pre-scaling is finally outputted.

On the contrary, if it is determined in step S902 that the pre-scalingis not unnecessary to execute, the pre-scaling is bypassed and the imagesize obtained through the post-scaling in step S905 is finallyoutputted.

In step S906, the image data scaled through the pre-scaling and thepost-scaling is synchronized with the output clock of the image sensor.That is, data timing synchronization process is performed.

FIG. 5 is a block diagram of the scaling ratio generator 250 illustratedin FIG. 3.

Referring to FIG. 5, the scaling ratio generator 250 includes a divider250-1, a plurality of comparators 250-2A to 250-2C, a selector 250-3, apost-scaling ratio determiner 250-4. The divider 250-1 outputs thescaling ratio given by dividing SCALEM by SCALEN using the scalingfactor. The plurality of comparators 250-2A to 250-2C have differentreference values ranging from 1/2 to 1/8 for comparing the scaling ratiowith a preset scaling ratio. The selector 250-3 outputs thecorresponding pre-scaling ratio among the outputs of the comparators250-2A to 250-2C. The post-scaling ratio determiner 250-4 determines thepost-scaling ratio using the pre-scaling valid signal (the output of thecomparator 250-2C having the scaling ratio reference value of 1/2) andthe selected pre-scaling ratio.

Although the post-scaler 250 having the scaling ratio of 1 to 1/8 hasbeen described in the above embodiment, the present invention can alsobe applied to a greater or smaller scaling ratio.

An operation of the post-scaler 250 will be described below in detail.

The divider 250-1 calculates the scaling ratio by dividing the scalerfactor SCALEM by the scaler factor SCALEN. The scaling ratio outputtedfrom the divider 250-1 is inputted to negative (−) terminals of thecomparators 250-2A to 250-2C having the reference values 1/2, 1/4, and1/8, respectively.

When the scaling ratio is greater than 1/2, the outputs of all thecomparators 250-2A to 250-2C are a logic low and the scaler valid signalis also a logic low. Consequently, the pre-scaler 251 is turned off. Atthis point, the scaling ratio becomes SCALEM/SCALEN.

When the scaling ratio is less than or equal to 1/2 and greater than1/4, the output of only the 1/2 comparator 250-2C is a logic high. Thepre-scaling ratio becomes 1/2. At this point, the post-scaling ratiobecomes (SCALEM/SCALEN)/(1/2).

When the scaling ratio is less than or equal to 1/4 and greater than1/8, the outputs of only the 1/2 comparator 250-2C and the 1/4comparator 250-2B are a logic high. The pre-scaling ratio becomes 1/4.At this point, the post-scaling ratio becomes (SCALEM/SCALEN)/(1/4).

When the scaling ratio is greater than 1/2, the scaler valid signal is alogic low. When the scaling ratio is less than or equal to 1/2, thepost-scaling ratio is a logic high.

FIG. 6 is a block diagram of the pre-scaler 251 illustrated in FIG. 3.

Referring to FIG. 6, the pre-scaler 251 includes a plurality of ANDgates 251-1A to 251-1C, an address shift coefficient selector 251-2, apre-scaler address generator 251-3, and a pre-scaler data sampler 251-4.The AND gate 251-1A has one terminal receiving the reference value of1/8 and another terminal receiving the pre-scaling ratio, the AND gate251-1B has one terminal receiving the reference value of 1/4 and anotherterminal receiving the pre-scaling ratio, and the AND gate 251-1C hasone terminal receiving the reference value of 1/2 and another terminalreceiving the pre-scaling ratio. The address shift coefficient selector251-2 selects the shift coefficient of the corresponding address usingthe outputs of the AND gates 251-1A to 251-1C. The pre-scaler addressgenerator 251-3 generates the pre-scaler row/column addresses byshifting the addresses from the timing controller 21 as much as thecorresponding coefficient selected by the address shift coefficientselector 251-2. The pre-scaler data sampler 251-4 samples the originalimage data and the data stored in the line memory 23 through thepre-scaler row/column addresses and outputs the pre-scaler image data.

The pre-scaler 251 operates only when the scaler valid signal is a logichigh, and shifts the row/column addresses provided from the timingcontroller 21 in each bit according to the pre-scaling ratio determinedby the scaler ratio generator 250. That is, a 1-bit shift is performedwhen the scaling ratio is 1/2, a 2-bit shift is performed when thescaling ratio is 1/4, and a 3-bit shift is performed when the scalingratio is 1/8. Through this shift process, the pre-scaler row/columnaddresses are generated.

Meanwhile, even in the same pre-scaling ratio, the pre-scaler row/columnaddresses are differently generated when the image scaler is performedin the full color data level and in the bayer data level.

By outputting only data located at positions matched with the pre-scaleraddress position, which is newly constructed among the original imagedata through the pre-scaler data sampler 251-4, the output data of theimage sensor can be implemented to match with the pre-scaling ratio.

In various manners, the output data of the pre-scaler 251 can bedetermined using the data of the previous line and the currentlyinputted data through the line memory 23 at the position where theaddress is matched.

Accordingly, the image quality of the pre-scaler output image isdetermined by the method of determining the output data.

FIG. 7 is a block diagram of the post-scaler 252 illustrated in FIG. 3.

Referring to FIG. 7, the post-scaler 252 includes a post-scaler addressgenerator 252-1, transmission gates 252-3A and 252-3B, and a post-scalerdata sampler 252-2. The post-scaler address generator 252-1 receives therow/column addresses from the timing controller 21, the pre-scalerrow/column addresses, the pre-scaler valid signal, and the post-scalingratio and generates the post-scaler row/column addresses. Thetransmission gate 252-3A receives the pre-scaler valid signal and itsinverted signal through gates of NMOS and PMOS transistors and outputsthe pre-scaler image data. The transmission gate 252-3B receives thepre-scaler valid signal and its inverted signal through gates of NMOSand PMOS transistors and outputs the original image data. Thepost-scaler data sampler 252-2 samples the original image data or thepre-scaler image data through the post-scaler row/column addresses andoutputs the post-scaler image data.

The post-scaler address generator 252-1 selects one of the pre-scalerrow/column post-scaling ratio and the row/column address of the entiresize of the image sensor, which is generated by the timing controller 21by using the post-scaling ratio and the pre-scaling valid signal in Eqs.(1) and (2), and then generates the post-scaler row/column addresses. Atthis point, like in the pre-scaler 251, the post-scaler row/columnaddresses are differently generated when the image scaler is performedin the full color data level and in the bayer data level.

Also, like the pre-scaler data sampler 251-3, the post-scaler addressgenerator 252-2 selects one of the original image data and thepre-scaler image data according to the pre-scaler valid signal andoutputs data at the position matched with the new post-scaler address.The image quality of the post-scaler output image is determined by themethod of outputting the output data.

FIG. 8A illustrates the output of the pre-scaler in the full color datalevel when the pre-scaling ratio is 1/4, and FIG. 8B illustrates theoutput of the pre-scaler in the bayer data level when the pre-scalingratio is 1/4.

Specifically, FIGS. 8A and 8B illustrate a case where the pre-scalingratio is 1/4 with respect to a 16×16 pixel array. Even though thepre-scaling ratios are equal to 1/4, the pre-scaler row/column addressis (1,5,9,13) in the full color data level and (1,2,9,10) in the bayerlevel, whereby the pre-scaler addresses are differently implemented.

Consequently, the data of the positions matched with the row/columnaddresses are outputted as the output data of the pre-scaler 251.

FIG. 9A illustrates an output of the post-scaler in a full color datalevel when the post-scaling ratio is 5/7 with respect to a post 14×14pixel array, and FIG. 9B illustrates an output of the post-scaler in abayer data level when the post-scaling ratio is 5/7 with respect to apost 14×14 pixel array.

Even though the post-scaling ratios are equal to 5/7, the row/columnaddresses is (1,2,3,5,6,8,9,10,12,13) in the full color data level and(1,2,3,4,5,6,9,10,11,12) in the bayer data level, whereby thepost-scaler addresses are differently implemented.

When the post-scaling ratio is greater than 1/2, it does not passthrough the pre-scaler. When the scaling ratio is less than 1/2, itpasses through the pre-scaler and is newly constructed like Eqs. (1) and(2). Therefore, the post-scaling ratio is always in a range from 1 to1/2.

For example, when the scaling ratio is 3/7, the pre-scaling ratiobecomes 1/2 and the post-scaling ratio becomes 6/7 by Eq. (2). When thescaling ratio is 6/7, the post-scaling ratio becomes 6/7 by Eq. (1).

Therefore, when the scaling ratio is 3/7 and 6/7, the post-scaling ratiobecomes 6/7 in both cases.

Like this, since the scaler method of the present invention can sharethe same post-scaling ratio, the post-scaler can be implemented in thesame configuration, thereby reducing the complexity of hardware.

The output data synchronizer 253 acts as a first input first out (FIFO)that synchronizes the image scaler output data with a random period,which is outputted from through the post-scaler, with the output clockof the image sensor and then outputs the data at a constant period. Theoutput data synchronizer 253 is configured with a plurality of linememories. Also, the output data synchronizer 253 constantly matches theintervals of the respective lines, as well as the constant period of theoutput data of the image sensor.

FIG. 10 is a flowchart diagram illustrating an algorithm of generatingrow/column addresses for the image scaling.

Referring to FIG. 10, in step S101, it is determined whether an imagescaler is executed or not. If the image scaling is unnecessary, therow/column addresses are unnecessary to generate. Therefore, therow/column addresses from the timing controller are outputted withoutchange.

In this case, the size of the output image from the pixel array isidentical to that of the output image from the image sensor.

On the contrary, in step S102, if the image scaling is necessary, it isdetermined whether the scaling is executed in a full color RGB datalevel or a bayer mosaic pattern data level. The scaling in the fullcolor RGB data level is referred to as a full color scaling (FCS), andthe scaling in the bayer mosaic pattern data level is referred to as abayer mosaic scaling (BMS).

Unlike the full color data, the bayer data has one color information perpixel in B/Gb or R/Cr line. Therefore, an address of the B/Gb or R/Grpixel has to be generated at the same time. Thereafter, when thepre-scaling is executed according to the scaling ratio, the row/columnaddresses for the pre-scaling are generated and used in the pre-scaler.Also, when the post-scaling is executed, the row/column addresses forthe post-scaling are generated and used in the post-scaler.

When the FCS or BMS is selected in step S102, the row/column addressesfor the pre-scaling and the post-scaling are generated through stepsS103 to S109.

In accordance with the present invention, arbitrary scaling factors(SCALEM, SCALEN) are received and the scaling ratio (=SCALEM/SCALEN) isdetermined through the scaling ratio generator. Then, the row/columnaddresses of the entire size of the image generated by the timingcontroller are reconfigured using the row/column addresses correspondingto the scaling ratio. Consequently, only data located at positionsmatched with the row/column addresses newly generated are outputted.

The image size can be arbitrarily adjusted through the pre-scaler andthe post-scaler. When the scaling ratio is greater than 1/2, thepre-scaler is off and the image size is adjusted only by thepost-scaler.

Since the size of the output image of the image sensor can bearbitrarily changed according to the scaling ratio, the image size canbe adjusted according to the requirement of an image displaying systemsuch as the digital camera or mobile phone.

Typically, in case that a scaling ratio is small, a whole image sizeshould be converted to a very small size. Thus, damage in an image isgenerated. However, in case that the scaling ratio is small, apre-scaler serves a role in controlling an image size to a medium sizeof the scaling ratio to reduce the damage in the image.

Therefore, it is possible to satisfy the technical requirements of thehigh image quality/high resolution of the capture image and thesmall-sized image display. Thus, it is easy to adjust the image sizeregardless of the size of the original image in the image sensor.

Also, the hardware of the scaler can be simplified by separatelyinstalling the pre-scaler and the post-scaler depending on the scalingratio, thereby increasing the degree of integration.

Although the CMOS image sensor has been taken as an example, the presentinvention can also be applied to various kinds of image sensors.

The present application contains subject matter related to the Koreanpatent application No. KR 2005-0015506, filed in the Korean PatentOffice on Feb. 24, 2005, the entire contents of which being incorporatedherein by reference.

While the present invention has been described with respect to theparticular embodiments, it will be apparent to those skilled in the artthat various changes and modifications may be made without departingfrom the scope of the invention as defined in the following claims.

1. An image sensor comprising: a timing controller for controlling anoverall operation of the image sensor; a line memory for storing digitalsignals corresponding to a plurality of images; and a scaler forgenerating a row/column address by calculating a scaling ratio accordingto a scaling factor of a desired image size from the timing controller,to scale the corresponding image, wherein the corresponding image of thedesired size is outputted through a pre-scaler and a post-scaler coupledto each other in the image sensor, and coupled to a scaling ratiogenerator, a timing controller and the line memory, and selectivelyexecuted according to the scaling ratio.
 2. The image sensor of claim 1,wherein the pre-scaler and the post-scaler are embedded in the scalerand the scaler is embedded in the image sensor.
 3. The image sensor ofclaim 2, wherein, when the desired image size is M×N, where M representsthe number of columns and N represents the number of rows, and M and Nare positive integers, the scaling ratio is SCALEM/SCALEN, where SCALEMand SCALEN are the scaling factors.
 4. The image sensor of claim 3,wherein the scaling ratio generator determines a pre-scaler valid signaland a pre-scaling ratio, according to the scaling ratio.
 5. The imagesensor of claim 4, wherein the pre-scaler generates a pre-scalerrow/column address according to the pre-scaling ratio only when apre-scaler valid signal is generated.
 6. The image sensor of claim 5,wherein when the pre-scaler is not executed, the scaling ratio from thescaling ratio generator is used as the post-scaling ratio in thepost-scaler, and when the pre-scaler is executed, the post-scaling ratiobecomes [(SCALEM/SCALEN)/(the scaling ratio)], where SCALEM and SCALENare the scaling factor.
 7. The image sensor of claim 6, wherein when thepre-scaler is off, the post-scaler receives row/column address from thetiming controller and generates new row/column address corresponding tothe scaling ratio, and when the pre-scaler is on, the post-scalerreceives address from the pre-scaler and generates new row/columnaddress corresponding to the post-scaling ratio.
 8. The image sensor ofclaim 4, wherein the pre-scaler valid signal determines an on/offoperation of the pre-scaler.
 9. The image sensor of claim 5, wherein thepre-scaler operates only when the scaler valid signal is a logic high,and shifts the row/column address from the timing controller accordingto the pre-scaling ratio determined by the scaler ratio generator. 10.The image sensor of claim 6, wherein the post-scaling ratio has a valuein a range from 1 to 1/2.
 11. The image sensor of claim 1, wherein thepre-scaler comprises: a plurality of AND gates having one terminal forreceiving different reference values and having another terminal forreceiving a pre-scaling ratio; an address shift coefficient selector forselecting a shift coefficient of a corresponding address through outputsof the AND gates; a pre-scaler address generator for generatingpre-scaler row/column addresses by shifting the addresses from thetiming controller as much as a corresponding coefficient selected by theaddress shift coefficient selector; and a pre-scaler data sampler forsampling original image data and the data stored in the line memorythrough the pre-scaler row/column addresses and outputting thepre-scaler image data.
 12. The image sensor of claim 7, wherein evenwhen the shift coefficients are equal, the post-scaler has differentpost-scaler row/column addresses in a full color data level and a bayerdata level.
 13. An image sensor comprising: a timing controller forcontrolling an overall operation of the image sensor; and a scaler forgenerating a row/column address by calculating a scaling ratio accordingto a scaling factor of a desired image size from the timing controller,to scale the corresponding image, wherein the corresponding image of thedesired size is outputted through a pre-scaler and a post-scaler coupledto each other and being separately installed in the scaler based on thescaling ratio, and coupled to a scaling ratio generator, a timingcontroller and a line memory, and selectively executed according to thescaling ratio.
 14. The image sensor of claim 13, wherein the imagesensor is a complementary metal oxide semiconductor image sensor.
 15. Animage sensor comprising: a timing controller for controlling an overalloperation of the image sensor; a line memory for storing digital signalscorresponding to a plurality of images in line unit; an image signalprocessor for processing the plurality of images by using thecorresponding digital signal stored in the line memory so as to improveperformance of the image sensor; and a scaler for generating acorresponding row/column address by calculating a scaling ratioaccording to a scaling factor of a desired image size from the timingcontroller, to scale the corresponding image, wherein the correspondingimage of the desired size is outputted through a pre-scaler and apost-scaler coupled to each other in the image sensor, and selectivelyexecuted according to the scaling ratio, the post-scaler comprising apost-scaler address generator, a plurality of transistors and apost-scaler data sampler.
 16. The image sensor of claim 15, wherein thescaler determines whether to execute the pre-scaling according to thescaling ratio and selectively executes the pre-scaling to primarilyadjust the image size, and determines whether to execute thepost-scaling and selectively executes the post-scaling.
 17. The imagesensor of claim 16, wherein when the desired image size is M×N, where Mrepresenting the number of columns and N representing the number of rowsare positive integers, the scaling ratio is SCALEM/SCALEN, where SCALEMand SCALEN are the scaling factor.
 18. The image sensor of claim 17,wherein the scaling ratio generator determines the pre-scaler validsignal and the pre-scaling ratio according to the scaling ratio, and thepre-scaler valid signal determines an on/off operation of thepre-scaler.
 19. The image sensor of claim 18, wherein the pre-scalergenerates a pre-scaler row/column address according to the pre-scalingratio only when the pre-scaler valid signal is generated, and generatesan image of the pre-scaled size by sampling only data located atposition matched with the pre-scaler row/column address in the linememory.
 20. The image sensor of claim 19, wherein when the pre-scaler isnot executed, the scaling ratio from the scaling ratio generator is usedas the post-scaling ratio in the post-scaler, and when the pre-scaler isexecuted, the post-scaling ratio becomes [(SCALEM/SCALEN)/(the scalingratio)], where SCALEM and SCALEN are the scaling factor.
 21. The imagesensor of claim 17, wherein the scaling ratio generator includes: adivider for dividing the scaling factor (SCALEM) by the scaling factor(SCALEN) and outputting the resulting value as the scaling ratio; aplurality of comparators for comparing the scaling ratio with a presetscaling ratio, the comparators having different reference values; aselector for outputting a corresponding pre-scaling ratio among theoutputs of the comparators; and a post-scaling ratio determiner fordetermining the post-scaling ratio using the pre-scaling valid signaloutput from a one of the plurality of the comparators, and the selectedpre-scaling ratio.
 22. The image sensor of claim 21, wherein each of theplurality of comparators is configured with a reference value rangingfrom 1/2 to 1/8.
 23. The image sensor of claim 21, wherein when thescaling ratio is greater than 1/2, each of the outputs from theplurality of the comparators is logic low, and the pre-scaler is turnedoff.
 24. A method of operation of an image sensor, the methodcomprising: scaling an image by generating a row/column address ofcorresponding image data upon calculating a scaling ratio according to ascaling factor of a desired image size, wherein the corresponding imageof the desired size is outputted through a pre-scaler and a post-scalercoupled to each other in a scaler embedded in the image sensor, thepre-scaler and the post-scaler being selectively executed by the scaleraccording to a scaling ratio.
 25. The method of claim 24, furthercomprising: prior to scaling the image, determining whether the scalingis to be executed in an RGB data level or a bayer mosaic pattern datalevel and generating the row/column address of the corresponding imageat a selected time indicative of whether the scaling is to be executedin the RGB data level or the bayer mosaic pattern data level.